from math import sqrt 


num = int(input('请输入一个正整数: ')) 
if num == 1: 
    print('1是素数') 
else: 
    end = int(sqrt(num)) 
    for x in range(2, end + 1): 
        if num % x == 0: 
            print(f'{num}不是素数') 
            break 
        else: 
            print(f'{num}是素数')

